I need help with 18-20 inch wheels

[197DMach1 10]

Hello everyone I'm new here and happy I found such a great forum. I'm looking for some help from you guys. I have a 1970 Mach 1 that I'm finishing up and now need wheel advice/help.

 

I'm going with the Boss 338's and trying to figure out the best setup. My options are as follows:

 

18s (for front)

18x8 Offset +2 mm, Backspace 4.517

18x8 Offset +14 mm, Backspace 4.989

 

20s (for rear)

20x8.5, Offset +14 mm, Backspace 5.239

20x8.5, Offset +28 mm, Backspace 5.79

 

I would appreciate all your help.

 

Thanks

[ForceFed70 14]

Aim for 5" BS front and 5.5" rear. I found that to be almost perfect for my 18's.

 

If you plan on lowering your car, you will need to roll the front fender lips if you want to put rubber on those rims that doesn't look goofy (by goofy I mean the wheel being wider than the rubber).

[EastYorkStang 63]

What rubber do you have now? Most tire manufacturers have spec sheets listing the dimensions of their tires. Compare what you have with what you are going with.

[69ISH 10]

I found this to be a great Tyre/Rim?Backspace calculator.

http://www.rimsntires.com/rt_specs.jsp

[ForceFed70 14]

Up front I run a 245/40/18 tire on an 18x8 wheel.

 

The wheels were originally 9" wide, but I didn't like the goofy look and couldn't squeeze any wider rubber in the wheel well. I ended up having then narrowed 1" which worked great as the wheels had 6" of BS which was too much so I had to use a 1" spacer. When I got the wheels narrowed, the rubber looked much better and I got to ditch the spacers as 5" of BS seems about perfect.

[panteramatt 1]

Why go with 20's on a mach1? 18's should be about the limit on a classic car and the tires will be much cheapers and easier to get.

[Aw4g63 0]

Why go with 20's on a mach1? 18's should be about the limit on a classic car and the tires will be much cheapers and easier to get.

 

Personal preference? Kind of like the reason the radio has more than one station.